It is often desirable for a radiation detector to provide position sensitivity for detected radiation, in addition to the basic indication of whether or not radiation is present. Such position sensitivity is exploited in numerous applications, such as medical imaging. Positron emission tomography (PET) and single photon emission computed tomography (SPECT) are two examples of medical imaging techniques that rely on position sensitive radiation detection.
Accordingly, methods for providing detector position sensitivity have been extensively investigated for many years. One early example is considered by Anger in an article “Sensitivity, resolution and linearity of the scintillation camera” (IEEE Transaction on Nuclear Science, v13 n3 pp 380-392, June 1966). In this example, an electrical network is connected to an array of photomultiplier tubes (PMTs) such that the network outputs provide an indication of which PMT provided the detection signal (i.e., position sensitivity). Another approach that has been considered is the use of an array of small detectors having individual detector outputs. Such an array can provide pixel-level position information, where the array elements serve as the pixels.
However, such approaches for providing position sensitivity have noteworthy disadvantages in practice. In particular, complicated circuitry and/or a large number of output connections may be required. For example, the above-referenced approach of Anger requires four capacitors for each detector element, where the capacitance values of each of these numerous capacitors are critical for the accuracy of the position sensitivity. An individually addressed array of detector elements requires an output for each detector element. Since present day medical imaging techniques frequently make use of a large number of 2-D position sensitive detectors to provide 2-D and 3-D imaging, this complexity often becomes burdensome. Multiplexing approaches (e.g., as considered in U.S. Pat. No. 7,495,201) have been considered to reduce complexity.
However, there remains a need in the art for improved position sensitive detection, especially in connection with solid state detectors.